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WhoisThisDomain vs DomainTools Whois Lookup: catalog facts
WhoisThisDomain	DomainTools Whois Lookup
Free Freeware from NirSoft, free to use and redistribute unmodified.	Freemium Basic lookups are free, with deeper history and reverse WHOIS research on paid plans.
Windows	Web
Chooses the WHOIS server automatically by TLD Batch lookups and name-and-extension combinations	Domain ownership and IP address history in one lookup Shows whether a domain is available or for sale
Only queries WHOIS servers on port 43, not web-based WHOIS Proxy authentication with a user name and password is not supported	Free tier is limited Historical and reverse lookups are aimed at paying users
Downloadable app	Web application
Closed source	Closed source
License: Freeware	License not stated
No account needed	Not stated if an account is needed
Needs internet	Needs internet
Official website Full listing and sources Checked October 8, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.